1. Field of the Invention
This disclosure relates to an optical coherence tomography imaging apparatus, an imaging system, and a control apparatus and a control method for controlling an imaging range in a depth direction of an optical coherence tomography.
2. Description of the Related Art
An ophthalmic tomographic imaging apparatus such as an optical coherence tomography (OCT) enables three-dimensionally observing a state inside a tissue such as a retinal layer, for example. A time domain (TD)-OCT in which a broad band light source is combined with a Michelson interferometer, for example, has been known as a form of the OCT. The TD OCT acquires information about depth resolution by measuring interference light between the backscattering lights of a reference arm and a signal arm while changing the optical path of the reference arm. There has also been known a spectral domain (SD)-OCT in which a spectroscope is used instead of changing the optical path of the reference arm and the spectral light is detected by a line sensor to acquire an interferogram. Furthermore, there has been known a swept source (SS)-OCT using a method in spectral interference is measured by a single channel optical detector using a high-speed wavelength-swept light source as a light source (refer to U.S. Pat. No. 5,321,501).
In the OCT, the smaller the difference in optical path length between a reference beam and a measuring beam becomes, that is, the nearer the optical path length becomes to the same position (the coherence gate position), the better image quality can be obtained. Japanese Patent Application Laid-Open 2008-154941 discusses that the difference in optical path length between the reference beam and the measuring beam is changed according to a signal to noise ratio (SN) of an image.
However, a method for controlling the difference in optical path length is not necessarily suited to an imaging target object, so that an imaging range cannot be quickly set.